Click-to-Run is a new technology Microsoft are introducing to allow you to test out Office 2010 quickly and easily, by literally streaming the app to your computer from the Internet into a virtualised space.

This technology is one piece in Microsoft’s plan to make Office 2010 easier to obtain, including Office 2010 starter, an advert-supported, crippled version being sold to OEMs

Click-to-Run is designed to sweeten the experience of trying and buying Office by avoiding a lengthy download and multi-step unpacking / installing process. Click-to-Run always sends you the latest up to date version, so you don’t need to download update after update, even after you’ve installed Office.

The software delivered by Click-to-Run is also virtualised so that you can cleanly run it side by side with other versions of Office software to evaluate changes.

Click-to-Run products also take up about half the disk space of normal products, they repair more completely, and they won’t break other software installed on the PC because they have private copies of all of their files and registration.

Click-to-Run is not a new Office “product”, it’s a new way of delivering and updating the products with which you are already familiar. Click-to-Run delivery is available for both the Office Home and Student 2010, and Office Home and Business 2010 products. It has full language support, and will work on both 32-bit and 64-bit Operating Systems (although only the 32-bit version of Office is actually run on both platforms).

Interestingly, users get a "Q:" drive, a virtual drive where the Click-to-Run software resides.

The streaming aspect is probably the most interesting aspect—much like watching a video in a web-page, not all of the video has to download before it begins playing. With Click-to-Run you can start using Office before all of the functionality has even downloaded! (Microsoft state that you can be running from between 90 seconds and five minutes, depending on connection speed)

When you try to use functionality in Office that isn’t yet downloaded, Click-to-Run fetches it for you, resulting in a small pause, or for larger downloads a tray icon and bubble to explain, allowing you control over the download process.

With a user base as large as Office, Microsoft must make the whole trial / upgrade experience a wholly smooth affair, without the fear of having to mess your system up, or break your current Office install. Users should feel confident that they can evaluate the new Office without having to set aside a date for it for fear of total registry fallout.

Click-to-Run could end up delivering more than just Office in the Future, but that might depend upon just how well received Click-to-Run is received by users. It would certainly lay the path for a good 'Software as a Service' system, as native code could be streamed to your computer so that you always have the most up to date version of a software, without it having to be an HTML web-app.

As I take an interest in UI, my concern with the streaming aspect is that despite the wait to download and install an application traditionally, at least it operates quickly when you do get it open. The streaming aspect of Click-to-Run—whilst saving time up front—could only serve to irritate users with sluggish performance waiting for functionality to download when you ask for it. In the world of the web, you lose 1% of your traffic for every 10ms of additional lag, people are put off literally that quickly. I will have to reserve judgement until I get to try out the entire process, hopefully soon.